This solution will teach you how to run FPS Monitor in async, detached from Steam: your current Steam status won't be "running FPSMonitor" anymore and FPS Monitor will be launched just like if you started it outside of Steam.

1. Create the following "RunAsync.vbs" script into the same dir of FPSMonitor.exe:
   (remember to change the path accordingly to your setup)
   
   Set WshShell = CreateObject("WScript.Shell") WshShell.Run """D:\SteamLibrary\steamapps\common\FPS Monitor\FPSMonitor.exe""", 0, False
2. Set as Steam launch parameter for FPSMonitor (right mouse button and choose Properties):
   (remember to change the path accordingly to your setup)
   
   "D:\SteamLibrary\steamapps\common\FPS Monitor\RunAsync.vbs" %command%

Done.

⚠️ This solution, as a side effect, can cause troubles if you need to re-register FPS Monitor through Steam, for example after a program update. In this case just temporarily disable the launch parameter option (2) to run it in sync with Steam and let it update & register as usual.